**14. Conclusions**

In 2006, du Mesnil de Rochemont et al. [46] found three (6%) occlusions of filters by debris or clots in a series of 50 CASs. In a series of 162 CASs, Piñero et al. found filter occlusion in four (2.5%) patients during the procedure [48]. It is predicted that these cases will become significant infarcts due to the large size of the particles because it was sufficient to obstruct the filter pores up to total occlusion of the flow. Piñero et al. [48] assume that, without the use of a filter in

There was no case of filter occlusion by debris or thrombi in our series. Vasospasms related to the filtering devices were short-lived and without hemodynamic impairment. Other compli‐ cations related to the filters were not found in this series. Filter occlusion leading to a stopped flow is a rare occurrence. It was more observed with the use of the first generation of EPI®

While the first step in CAS, which includes catheterization, the positioning of the guide catheter and the passage of the filter over the stenosis, occurs without protection, the phases with the greatest number of emboli released from plaque are the implantation of the stent and the angioplasty by balloon. An overload of the filter protection system is the angioplasty by balloon. Piñero at al. [111] showed that the more balloon dilations are applied to CAS, the greater the load of emboli found in the filters. Therefore, physician experience is necessary to

Unfortunately, the other technique currently used in the treatment of carotid stenosis – CEA – also has ischemic complications [59] and more brain emboli than CAS [37,83]. Another common complication in CEA is lesions to the cranial nerves and cardiac infarction [117,118]. Comparative studies between CEA and CAS found a greater number of NF after CAS than after CEA. However, the lesions in the DWI after CAS are significantly smaller than after the endarterectomy. Analyzing the NF in the DWI after CAS and endarterectomy, Roh et al. [78] reasoned that the lesions in diffusion after CAS are generally asymptomatic and that the lesions in DWI associated with symptoms are more frequent in CEA [37,78]. In recent years, the materials used in CAS have been improved to reduce complications. DWI can be used as a tool in this evolving analysis of materials and also in the technical

Our study shows some limitations. Data collection of a control group without the use of cerebral protection to prove the device's effectiveness is incorrect based on our ethical views of the procedure, but it is a limitation of the study. However, other published studies that conducted CAS with and without protection systems clearly show a smaller number of NF [35,37] and lower risk of ischemic events [33,38] after CAS in the groups where the devices

The formation of emboli can be impeded by antiplatelet and anticoagulant medications [76], but this is not the focus of our research shown here. In neuroradiology procedures, the prevalence of resistance to aspirin varied from 2 to 21%, and resistance to clopidogrel varied from 43 to 52% [119-121]. This result is extremely important because atheromatous plaques and superimposed thrombi are the main source of microemboli during CAS. A recent study from Song et al. [76] using the VerifyNow system showed that the frequency of resistance to

these cases, the morbidity of their series would increase from 4 to 6.5%.

filters, where the diameters of the pores were only 80 µm [46,116].

use the balloon as delicately as possible.

190 Carotid Artery Disease - From Bench to Bedside and Beyond

improvement of neurointervention.

were used.

The use of protection systems aims to avoid massive embolism, which occasionally happens. However, a perfect cerebral protection system is not commercially available. While cerebral protection with filters is effective, it is necessary to develop new protection devices that are more effective and can be occlusive systems with a lower profile and greater ease of use. Both techniques, angioplasty with stent (with filter or flow occlusion systems) and endarterectomy, are involved in cases of intracranial embolism per treatment.

New restriction foci (NF) in diffusion were present in half of the patients after CAS with cerebral protection and were most frequently located in the ipsilateral area (77.19%), suggest‐ ing that the filters did not prevent all microemboli. New restriction foci in DWI after CAS were located in regions (22.81%) different than in the angioplasty and were associated with diagnostic catheterization. Therefore, long neurointerventionist medical training should be required before CASs are performed.

The NF in DWI after CAS were mostly small in diameter (<10 mm in 91.53%) and were always clinically silent (100%) in our study.

The presence of cerebral infarcts in the T2 sequence in the initial MRI was the only factor that significantly predisposed the appearance of new restriction foci in DWI after CAS. Thus, the risk of microemboli was directly related to intrinsic factors of the patient. Other demographic factors and aspects related to the angioplasty technique were not statistically significant to the occurrence of NF in our study. There was a tendency for other factors, such as the triaxial access technique, asymptomatic patients, and an eccentric filter, to be involved in the appearance of a smaller number of NF after CAS.

The appearance of microemboli attributed to catheterization and not angioplasty with stent shows that proper training for medical specialists in cervical and cerebral circulation (neuro‐ interventionists) can be key to reducing risks for patients. General specialists in vessels (vascular surgeons) and coronary circulation (cardiologists) generally do not have specific training for cervicocerebral circulation; most of their training focuses on the aorta and coronary arteries, respectively. We therefore recommend that angiographies to diagnose cervical and cerebral circulation and carotid angioplasty be conducted by interventional neuroradiologists to reduce the risk of emboli.

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To maintain cerebral flow during the endovascular carotid treatment, CAS with filter is the first choice in cases of serious stenosis. The use of occlusive systems is promising but requires more technical development to reduce the risks associated current systems.
